The Hydrosphere is the Earth's water envelope. The Hydrosphere contains mostly the seas and oceans that surround the Earth's continents. The Hydrosphere also contains the small percentage of the Earth's water that exists underground.

Streams and Lakes are made up of only 1% of the Hydrosphere but they are the Earth's greatest landscape changer and provide drinking water for humans and animals alike and important animal habitats.

Other noders should feel free to elaborate.